19 AIM-1SL & AIM-2SL Hardware Manual
© 2011 Apollo Security Inc.
3.6 Reader Input Wiring
The AIM-1/2SL has four input circuits which have different functions according to the mode used (Paired or
Unpaired). These inputs can be configured as UL Grade “B” (unsupervised) or UL Grade “A” (supervised).
The selection of supervised / unsupervised is made by changing DIP switch number 8. If in the OFF position,
the inputs for
both
readers are configured as unsupervised, if in the ON position
both
inputs are configured
as supervised. It is not possible to have both unsupervised and supervised inputs at the same time, all inputs
must be in the same configuration. If the inputs are configured as unsupervised, the door contact, exit
pushbutton, and auxiliary alarm contacts should be connected directly to the wiring terminals without using
any end of line terminating resistors. If the inputs are configured as supervised, the contacts must be
connected to end of line terminating resistors before being connected to the input terminals. Use of ATM-30
(part number 470-031) terminator is recommended.
3.6.1 Input Supervision (Overview)
Unsupervised, normally closed inputs will have a short circuit (0 ohms) when the circuit is in the secure state
and an open circuit (infinite ohms) when the circuit is in the unsecured state. This is a simple connection that
does not require addition of any resistors. The drawback to this type of connection (unsupervised) is that if
the two wires touch together (either accidentally or intentional sabotage) the reader will permanently detect
the circuit as being in the secure state. This effectively prevents all alarm generation. This situation is not
very secure and should not be used in any situation that requires maximum security. Unsupervised, normally
open inputs will have an open circuit (infinite ohms) when the circuit is in the secure state and a short circuit
(0 ohms) when the circuit is in the unsecured state. The same situation will occur as stated above if the wires
are cut (permanent secure). Very low security.
The AIM-1/2SL reader interface allows configuration of the inputs to the “supervised” mode. This is designed
to prevent the security breach that is possible using the “unsupervised” mode mentioned above. In the
supervised state, normally closed inputs will have approximately 300 ohms when in the circuit is in the
secure state and 10K ohms when in the unsecured state. If the wires are shorted together or cut
(accidentally or intentionally) the reader will instantly detect this (0 ohm or infinite ohm) condition and
immediately report this as a circuit fault. The reader will not confuse this condition with a valid secure
condition. Normally open, supervised inputs should be 10K ohms when secure and 300 ohms when
unsecured. Either way, security is greatly enhanced. TO TAKE FULL ADVANTAGE OF THE INCREASED
SECURITY PROVIDED BY INPUT SUPERVISION, THE END OF LINE TERMINATING RESISTORS
SHOULD BE ON THE EXTREME END OF THE CABLE, FARTHEST FROM THE READER. In many cases
it is possible to mount the resistors inside the housing of the input device.
NOTE: ATM-30 end of line resistors (or an equivalent substitute) are designed to work with the AIM-1/2SL
supervision values on STANDARD AIM-1/2SL interfaces. The AIM-1/2SL is available by special order with
custom resistor values. In the case of improper function of the supervision, verify what type of AIM-1/2SL is
installed in the system.
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